// C# reference reading: 

// http://www.tutorialspoint.com/csharp/csharp_classes.htm

// http://www.tutorialspoint.com/csharp/csharp_inheritance.htm

// http://www.tutorialspoint.com/csharp/csharp_polymorphism.htm

​

using System;

​

namespace TreeMap

{

   public class TreeMap

   {

        private TreeMapNode topNode = null;

        public void Add(IComparable key, object value) 

        {

            if (topNode == null)

            topNode = new TreeMapNode(key, value);

                   else

                     topNode.Add(key, value);

        }

        public object Get(IComparable key) 

        {

            return topNode == null ? null : topNode.Find(key); }

        }

        internal class TreeMapNode 

        {

            private static readonly int LESS = 0; 

            private static readonly int GREATER = 1; 

            private IComparable key;

            private object value;

            private TreeMapNode[] nodes = new TreeMapNode[2]; 

            public TreeMapNode(IComparable key, object value)

            {

                   this.key = key;

                   this.value = value;

            }

            public object Find(IComparable key) 

            {

                if (key.CompareTo(this.key) == 0) 

                    return value;

                return FindSubNodeForKey(SelectSubNode(key), key); 

            }

            private int SelectSubNode(IComparable key)

            {

                return (key.CompareTo(this.key) < 0) ? LESS : GREATER;

            }

            private object FindSubNodeForKey(int node, IComparable key) 

            {

                return nodes[node] == null ? null : nodes[node].Find(key); 

            }

            public void Add(IComparable key, object value) 

            {

                if (key.CompareTo(this.key) == 0) 

                    this.value = value;

                else

                    AddSubNode(SelectSubNode(key), key, value);

            }

            private void AddSubNode(int node, IComparable key, object value) 

            {

                if (nodes[node] == null)

                    nodes[node] = new TreeMapNode(key, value); 

                else

                    nodes[node].Add(key, value);

            }

    } 

}